Weight Puzzles

Sample Puzzles

Find below couple of weights and balance scale related puzzle questions. We are also mentioning the difficult level as per our perception. Our opinion may differ from yours.

Weight Puzzle Number 1

Here is a puzzle question of average (2/5; 5/5 is most difficult) difficulty level –

Among 12 identical looking golf balls there is one that is defective in weight. It is either heavier or lighter than the standard one. You have a balance Scale. You can only weigh 3 times to find out which one is defective and whether it is heavier or lighter.

Explain how will you be able to find the defective ball.

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Weight Puzzle Number 2 –

How many pre-measured weights do you need if you have got a balance scale in order to measure the weight of an object in the right pan of the balance scale. The weight of the object could be any exact number of Kilograms up to at least 120 Kg? Please also mention the weight (in Kgs) of the weights.

Leave your answer below by writing in the comment area!

How many pre-measured weights (for the left pan of your balance scale) do you need in order to measure the weight of an object in the right pan of the balance scale (you should be able to measure any exact number of ounces up to at least 120 ounces)?
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Vineet Patawari

Hi, I'm Vineet Patawari. I fell in love with numbers after being scared of them for quite some time. Now, I'm here to make you feel comfortable with numbers and help you get rid of Math Phobia!

11 thoughts to “Weight Puzzles”

  1. Hi,

    For puzzle1.

    –> divide the balls in four groups, each group will contain 3balls.( Let it be A,B,C and D )

    W1: now weigh A and B
    CASE1: If A and B are equal in weight then defective ball will be in either C or D.
    CASE2: If A and B are unequal in weight then defective ball could be in A or B as its not mentioned that defected is lighter or heavier.

    W2: now remove any one of A or B and replace it by C (say B and C are new weights)
    –> if B and C are equal in weight, then acc to CASE1, D contains defective ball. and for CASE2, A contains defective ball.
    –> if B and C are unequal then acc to CASE1, C contains defective.
    –> once defective group is decided, keep it with you and eliminate the others.
    –> note that W2 will confirm you whether the defective ball is lighter or heavier.

    W3: now keep one-one ball of the defective group for weighing.

    –> if it weighs equal the spare/remaining ball is defective.
    –> if its unequal in weight, W2 will confirm whether lighter ball is defective or heavier one.

  2. Really dis site s doin gud…
    i feel dat it wud be more useful if d correct ans s linked wit d question which ll let us knw wthr v r rite r not…

  3. 1.first take 3 and 3 balls.If they don’t weigh equal then the defective ball is here in this bunch.if they weigh equal then defective ball is in the set of other 6 balls.Thus we have 6 balls in which we need to find out the defective one.

    2.now the bunch of other six balls are equal weighted..take 3 balls of from them and weigh them with the bunch of 3 balls of the above weighted..if they are equal then defective ball is in the other bunch of 3 balls and if they are not equal defective ball is in this 3 ball set.(if this set weighs heavier than the ideal group of 3 balls {that we have selected from the remaining set of 6 balls} than defective ball is heavier and vice versa..)

    3.now we have 3 balls..take any 2 and weigh them with the other equal set of 2 balls..if they weigh equal then the remaining ball is defective..and if they don’t weigh equal then the ball which is heavier(as we have assumed the set if 3 is heavier than ideal set in the second step.) is defective in the scale..

  4. for the first puzzle:12 balls
    divide the balls into 2 patrs(6)(6)
    place tem in two panels next..the one which is weighing heavier take dat and divide dose in into 2 equal parts (3)(3)
    nw repaet the same ting .nw which is weighing heavier take dose 3 balls and now
    dis is d 3rd measurment:
    nw palce 1_1 in each panel
    nw if dey are equal den d left is d ball we r searching for..else any of dose 2..

  5. divide 12 into 3 groups of 4 each
    put 4balls on each side
    1st if both equal then keep 2balls one side out of these 8 balls and 2 balls from remaining 4 balls.
    If both equal then put 1 ball from these 4balls and 1 ball from remaining 2balls.if both equal then remaining ball will b defective.If both are not equal then ball kept from remaining 2 will b defective.
    If group of 4 balls kept is not equal then leave 3rd group and take any 1 group from these 2 and keep 2balls on each side if both equal then defective will b from 2nd group remaining .

  6. if the condition is that we can weigh each ball three times then:-

    1)divide the balls in 6-6 and wieigh
    2)one with bigger wgt is taken and divided into 3-3
    3)if one is bigger and other is smaller then take the bigger 3 balls chunk and weigh 1-1 …if both are equal the left one is biiger one and the defctv one AND if one is bigger than the othr than the bigger one is defective and bigger.
    4)but if on 3-3 weighng the balance show that they are equal then take the smaller 6 chunk as was in step 1 and then divide it into 3-3 ..weigh them ……choose the smaller 3 chunk and weigh 1-1….if equal then the left one i s smaaler and defctv …if one is gr8ter than other then smaler one is smaller and defctv:)

    BUT IF CONDITION IS TO USE THE BALANCE ONLY THRICE THEN LOOK 4 OTHER ANS

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